1. Field of the Invention
The present invention relates to control apparatus and method for a hybrid vehicle which are capable of controlling each operating point of first and second motor torques and an the engine and each drive torque of the first and second motors/generators and the engine in a steady-state manner and in a transient manner to aim at their target values.
2. Description of the Related Art
A conventional technology which suppresses an excessive lack in a driving torque due to a partial consumption of a torque developed by each motor/generator into a speed variation in each motor/generator itself in a hybrid vehicle in which powers developed by the engine and two motor/generators are synthesized and outputted to a drive axle of a hybrid transmission is well known as will be described below.
When a gear ratio represented by a ratio between an engine speed and a drive axle revolution speed is varied, first motor/generator and second motor/generator consume a part of torque developed due to the revolution speed variations in the first and second motors/generators themselves. Then, at this time, the torque supplied from each of the first motor/generator and second motor/generator to planetary gear unit becomes lack. Consequently, this results in an excessive lack of the driving torque. A Japanese Patent Application First Publication No. 2000-324620 published on Nov. 24, 2000 exemplifies a previously proposed control apparatus for a hybrid vehicle in which lacks in torques of both of the first and second motor/generators is estimated from a variation rate of one of the first and second motor/generator revolution speeds. This torque lack is added to a torque target value of each of the first and second motor/generators to suppress the excessive lack in driving torque.